The present invention relates to an apparatus for holding a substrate, in particular a semiconductor substrate or wafer. The present invention furthermore relates to a method for treatment of a substrate.
Miniaturized components, for example integrated electrical circuits, are increasingly being produced on planar substrates. The prominent substrate type for components is semiconductor wafers which, during processing, are used not only as a mount but, owing to the capability to manipulate their conductance characteristics and the capability to structure them finely, are normally themselves part of the circuit. Hundreds of highly complex electronic circuit units can thus be produced on one semiconductor wafer.
In order to save space, to reduce costs and to improve the functionality of the components, very small structures are grown, applied to, etched or implanted in and on the semiconductor wafers. During this process, the structures must be tested repeatedly on the wafer and must be identified in order to verify the respective process step. Finally, the semiconductor wafers are normally sawed in order to obtain the individual circuit units (chips) from a semiconductor wafer.
In order to allow the structures to be produced, to be tested and to be sawed on a semiconductor wafer, the semiconductor wafers must be held in a well-defined position during the processing, must be supplied with well-defined electrical potentials, and/or must be subjected to well-defined environmental parameters, such as temperature or pressure. For this purpose, semiconductor wafers are normally placed on a semiconductor wafer holder (chuck). Owing to the high sensitivity of the semiconductor wafer surface to scratching, and the fragile nature of the brittle semiconductor material as the semiconductor wafer diameter increases, the semiconductor wafer holders must be designed such that the semiconductor wafer can be placed down, held and passed on again in a manner which protects it. The surface of the semiconductor wafer holders should also be such that scratching of the semiconductor wafers can be prevented.